Method for manufacturing black plastic article capable of transmitting infrared ray

ABSTRACT

A method for manufacturing black plastic article capable of transmitting infrared ray, which includes mixing a black colorant, produced by mixing several transparent colorants of different color, into a transparent resin used as support, and processing the resulting mixture to manufacture a black plastic article. Said black plastic article is capable to absorbing visible light and transmitting infrared ray, and may be used in combination with an infrared region-sensitive CCD camera. The infrared region-sensitive CCD camera can take photos of the subject in a long distance through the black plastic article, if sufficient infrared ray from a subject may penetrate the black plastic article.

TECHNICAL FIELD

The invention relates to a kind of plastic which is capable of absorbinglight and transmitting infrared ray, especially relates to a method formanufacturing a black plastic by mixing several colored transparentcolorants into the colorless transparent resin and relates to anapplication in the infrared photograph thereof.

BACKGROUND OF THE INVENTION

Generally, the black plastic article is mainly manufactured by mixingthe inorganic black colorants into the opaque plastic using as supportand then processing the resulting mixture. Most of said inorganic blackcolorants comprise the carbon black grains with a biggish diameter as amain part.

The carbon black grains exist as the original particles and always reactinto the polymer in the producing process. It is very difficult todiffuse said polymers due to the large inter-particle attractiontherein, as a result that the light is blocked when transmittingthrough.

The smaller the diameter of the carbon black grains is, the bigger thespecific surface area of the polymers is, as a result that more lightwill be absorbed to make the color thereof is seen blacker by theobserver then that of the carbon black grains with bigger diameter, asthe bigger grains will reflect more light. When using the carbon blackas the colorant, the blackness mainly depends on the absorption of thelight which happens in the interior of the carbon black grains, hence,for the carbon black with a certain concentration, the smaller thediameter is, the more absorption of the light is.

At present, the diameter of the original particulars of the commoncarbon black is about 100 nm, which is much smaller then the wavelengthof the light which is 400 nm.

As the general black plastic articles use the carbon black grains withbiggish diameter, the scattering therein and the functional group of—C—OH— on the surface thereon will effect the infrared absorptionspectra between 800 nm and 1000 nm.

Besides, as the general black plastic articles use the opaque plastic assupport, the scattering therein makes the infrared ray could nottransmit through.

For example, mix of a kind of minuteness carbon black colorant in themarket and the plastic to make a thin article. As said article could leta little light transmit through, the minuteness carbon black colorantused is called “transparent black colorant”. As said thin article couldlet a little light and infrared ray transmit through, it is always usedin the infrared remote controls of the home electronic products.However, said thin article could only let the infrared pulse transmitthrough, but the infrared image. Even if the thin article could let theinfrared image transmit through, the unclear image generated still couldnot be used in the infrared photography.

SUMMARY OF THE INVENTION

One aspect of the invention is providing a black plastic article capableof transmitting infrared ray to resolve the problem that the blackplastic article in the priority technology could not used in theinfrared photography

The technical project of the invention is:

1. Mixing to get a black colorant:

Based on the optical principles, mix two or more than two coloredtransparent colorants together to get a black colorant, for example, mixthe tricolor colorants, i.e., cyan, magenta and yellow together with asuitable proportion.

2. Manufacturing a black plastic article:

Mix said black colorant into a compatible transparent resin to form ablack mixture. As the transparent resin is a material with plasticity,said black mixture could be molded into a plastic article with variousshapes.

3. Manufacturing a suitable camera:

Remove the infrared cut filter in front of an infrared region-sensitiveCCD camera, or install a device which could be removed with infrared cutfilter in front of the image sensor, in order that when photographthrough said black plastic article, the generation of the overlay imagescould be avoided then, which are formed by the visible light and theinfrared, the infrared and the infrared.

The main features of the technical project are:

1. Said black colorant looks black, while it is capable of transmittinginfrared ray.

Said black colorant could absorb the visible light spectrum includingblue (B), red (R) and green (G), but the IR spectrum, i.e., it iscapable of transmitting infrared ray.

2. Said black plastic article is a smooth-faced black plastic articlemanufactured by mixing the black colorant into a compatible transparentresin.

The transparent resin of the black plastic article should have hightransparence with the order that said plastic article could be capableof transmitting infrared ray to generate the image for the infraredphotograph.

Said transparent resin in the black plastic article is mainly used assupport, which could be manufactured into a lot of plates, membranes andcontainers with various shapes and large bulks by the machines, the artsand crafts normally used in this technical field.

The surface of the black plastic article is smooth enough to avoid thescattering of the infrared ray transmitted into occurred by the roughsurface, in order to generate clear infrared image for the infraredphotograph.

3. In said infrared region-sensitive CCD camera, remove the infrared cutfilter and add a special infrared pass filter, in order to let theinfrared into image sensor and to avoid the excessive overlay images.

The technical effects of the adopted technical projects and features:

The first effect of this invention is that the easily got transparentcolorants and the compatible transparent resin could be manufacturedinto a lot of plates, membranes, containers and other correlatedproducts with large bulks and various shapes capable of transmittinginfrared ray by the common plastic process equipments and the matureplastic pigmentation art techniques.

The second effect of this invention is that the said black plastic istoo easy to transmit infrared ray, which makes an infraredregion-sensitive CCD camera do transmittance photography to get a clearand not overlay image.

The third effect of this invention is that, because the said blackplastic is capable of absorbing visible light, so it has the effect ofdarkroom and hide. In the application of propagation tests in thedarkroom and public safety, an infrared region-sensitive CCD camera canbe utilized to process a special function of multi-angle photograph andphotograph surveillance.

BRIEF DESCRIPTION OF THE DRAWINGS

The brief description of the drawings as follows:

FIG. 1 is a structure schematic diagram showing finished products of ablack plastic, which is capable of transmitting infrared ray.

FIG. 1A is a schematic diagram showing the composition of the blackcolorant.

FIG. 1B is a schematic diagram of the metal mold.

FIG. 1C is an application schematic diagram of the black plastic article15.

FIG. 2 is a tricolor map of the light.

FIG. 2A shows the energy sum of bicolor light.

FIG. 2B is a tricolor map of the colorant.

FIG. 3 shows a transparent thin plate M1 with the color of magenta.

FIG. 3A shows an opaque thin plate M12 with the color of magenta.

FIG. 4 is a diagram showing the overlay situation of the transparentthin plates with the colors of CMY tricolor.

FIG. 4A is a mathematics schematic diagram showing the CMY colorants andRGB lights.

FIG. 5 is a characteristic curve of the typical colors of the threereceptors of human eyes.

FIG. 6 is a schematic diagram showing the cut filter of a common CCDcolor camera.

FIG. 6A is a schematic diagram showing the cut filter of a CCD colorcamera of a previous patent.

FIG. 6B is a schematic diagram showing the cut filter of the CCD colorcamera of the present invention.

FIG. 7 shows a plate 71 of a black plastic.

FIG. 8 is a schematic diagram showing the color photography of a blackplate 71.

FIG. 8A is a schematic diagram showing the infrared photograph of ablack plate 71.

FIG. 9 is a schematic diagram showing the infrared photograph of twodifferent black plates.

FIG. 10 is a penetration schematic diagram of the cut filter of the CCDcolor camera of a previous patent.

FIG. 11 is a penetration schematic diagram of the cut filter of the CCDcolor camera of the present invention.

FIG. 12 is a schematic diagram showing the image generation situation ofthe infrared ray pass filter.

FIG. 13 is a cross-section diagram of a black colorant (carbon black).

FIG. 13A is a cross-section diagram of a black colorant 11.

FIG. 13B is a cross-section diagram of a thin black colorant (carbonblack).

FIG. 13C is a cross-section diagram of a thin black colorant 11.

FIG. 14 is a schematic diagram of the observation darkroom of thepropagation experiment.

FIG. 15 is a schematic diagram of the application in the counterfeitingidentification.

DETAILED DESCRIPTION

The primary principle structure contents of the invention are shown inFIG. 1 to FIG. 1C. Please refer to FIG. 1, the structure schematicdiagram showing a black plastic, which is capable of transmittinginfrared ray. In FIG. 1, mix said black colorant 11 and transparentresin 12 into a black mixture 13, and then mold said black mixture 13with a metal mold 14 with a polished internal mold to form a blackplastic article 15.

Please refer to FIG. 1A, the schematic diagram of black colorantcomposition.

In FIG. 1A, the composition method 111 of the black colorant 11 is tomix more than two kinds of unicolor transparent colorants 1111 togetherto present a black colorant 1112, mainly in order to present black andabsorb the visible light.

Please refer to FIG. 1B, the conditional schematic diagram of the metalmolds.

In FIG. 1B, the condition for the black plastic article 15 beinginjected into the metal mold 14 is that the internal mold 141 of themetal mold 14 must be polished. Wherein, the principal purpose is to letthe injected black plastic article 15 have a smooth surface, so as toavoid the infrared ray transmitted into to be scattered on the roughsurface.

Please refer to FIG. 1C, the application schematic diagram of blackplastic article 15.

In FIG. 1C, there is an object 161 on the right side of the blackplastic article 15, and an infrared region-sensitive infrared camera 162on the left side. Said camera 162 could photograph the object 161through the black plastic article 15 and transmit the image to the videodisplay 163 of the infrared camera 162 to show.

Explain the embodiment of this invention according to FIG. 1.

Firstly, in the method for manufacturing the black colorant 11, why mixmore than two kinds of the transparent colorants 1111 to compose acolorant 1112 which presents black? What is the purpose of mixing thetransparent colorants to form the black colorant?

For example, FIG. 1A illustrates that cyan, magenta, yellow and othertricolor (hereinafter, CMY) colorant are mixed together with equalproportion to produce a mixture 1112. Then, use a compatible plastic assupport to form the plastic articles of various colors. According to theexperience of the experienced color matching technician or thereferenced data, it is must be emphasized that the CMY colorants shouldnot be mixed together with an equal proportion, because that willpresent gray black or black.

However, it is emphasized in this invention that, the three colorantswith CMY colors must be mixed together with an equal proportion at thesame time. Because, in this invention, the obtained mixture is mainlyused to absorb all visible lights (not one hundred percents absorption).

Evidently, the method of this invention is different from that of thecommon plastic color matching process! This invention emphasizes thatthe CMY colorants used must be transparent!

Why the transparent tricolor CMY colorants should be used?

To let the infrared ray transmit through!

How to let the infrared ray transmit through? Details are listed asfollows:

Please refer to FIG. 2, the tricolor map of the light.

As shown in FIG. 2, the tricolor of the light are respectively the redlight with a main wavelength at 700 nm, the green light with a mainwavelength at 520 nm and the blue light with a main wavelength at 460nm, wherein the tricolor is named as RGB tricolor. In the optics field,all the visible lights are made up of the RGB tricolor light.

Please refer to FIG. 2A, the view showing an energy sum of the bicolorlight.

When mixing the color lights to form a new color light, the energy ofthe new one is the sum of the energies of the mixed ones. As shown inFIG. 2A, mix a red light and a green light having the same exposurearea. The exposure area of the obtained light is the same as that of theoriginal light, while the energy of the obtained light is increased.That causes the brightness of the obtained light increase.

It can be observed in the color light mixture tests: white light can beobtained after equal mixing the tricolor light. If first mix red lightand green light to get a yellow light, then mix the yellow light withblue light to get, a white light will also be obtained. A white lightcould also be obtained by mixing other color lights together. If aftermixing two kinds of color lights, a white light is obtained, then thesetwo kinds of color lights are called as the complementary color lights,and these two colors is called as the complementary colors.

One of the important characters of complementary colors is: one colorlight irradiates on an object of its complementary color, the colorlight will be absorbed. For example, a blue light irradiates on a yellowobject, then the yellow object presents black.

Please refer to FIG. 2B, the tricolor map of the colorants.

The tricolors of the colorants are cyan, magenta, and yellow,abbreviated as CMY.

Color can be divided into two main categories, i.e., achromatic colorand chromatic color. Achromatic color refers to white, black andgray-scale color made up of white and black.

Various kinds of objects have different colors under the lightirradiation. The colors of many objects are provided with scrawl and dyeof colorants. The materials, which are capable of making the colorlessobjects present color or making the colored objects change their colors,are called as the colorants.

The colorants have the solid shape and the liquid shape. The colorantscan be divided into dyes, organic pigments and inorganic pigments.

Dyes are completely transparent and soluble in solvent without thespread problem.

The organic pigment has a particle diameter of about 0.05-0.1 μm, issemi-transparent and unable to be soluble in solvent, and has lowspecific gravity. The inorganic pigment has a particle diameter of about0.5-1 μm, is opaque and completely unable to be soluble in solvent, hasheavy specific gravity, and is lightfast and heat-resistant.

Generally speaking, the pigments are any kind of granule particle, whilethe dyes are small granules soluble in molecular conditions.

The colorants and the color lights are two different things, but theyall have various colors. In the color lights, it is certain that the redlight, the green light and the blue light are the basic original colorlights. In many colorants, if there are several basic originalcolorants, which can not be obtained by mixing other colorants, butwhich can be mixed to form other colorants? It is found in the colorantmixture tests that when mixing the colorants with the tricolors of red,green and blue, just the same as those of the colored lights, althoughthe color range of the obtained mixtures is not as broad as that of themixtures of the colored lights, a lot of colorants still could be formedby mixing said colorants together.

But, for this invention, the main purpose of the color matching is toget a color most like the black. This invention does not care much aboutthe special colors, how broad the color range is.

Learned from FIG. 2B, the black colorant 11 could be obtained by mixingthe CMY tricolor colorants together or by mixing the RGB tricolorcolorants together. Like the black in FIG. 2B.

Actually in FIG. 2B, mix two of the red, green and blur colorantsequally, the obtained colorant still could absorb most part of thevisible light to present black or other dark color.

Hence, for this invention, any approach which could by used to obtainsaid black shown in FIG. 2B could be deemed as the method formanufacturing the black colorant 11, whatever said black is composed bytwo colorants (for example, the green and the magenta) or by threecolorants (for example, CMY colorants or RGB colorants).

From the perspective of energy, due to the energy loss, the color of thecolorant mixture is certain to be darker then the pre-mixture color.

When mixing the colorants, it is always said that subtract a kind orseveral kinds of unicolor lights from the white light to make thecolorant present another color (such method is also called as thesubtractive color method).

Please refer to FIG. 3, the thin color plate of transparent magenta.

As shown in FIG. 3, let the color light irradiate on an ideal, magenta,transparent and thin plate M1. According to the characters of thecomplementary color, the magenta thin plate M1 will absorb the G colorlight of the RGB color lights in the white light, and let the left R andB color lights transmit out. As shown in FIG. 2B, the magenta thin plateM1 presents transparently magenta.

Please refer to FIG. 3A, the thin color plate M2, which is magenta andopaque.

As shown in FIG. 3A, let the color light irradiate on a magenta, opaqueand thin plate M2. Based on the reflection and absorption characters,the magenta thin plate M2 will absorb the G color light of the RGB colorlights in the white light, and let the left R and B color lights reflectout. In the human eyes, the magenta thin plate M2 will present opaqueand magenta after the reflection.

The above explains that, the transparent refers to the opticaltransmission phenomenon, and the opaque refers to the light reflectionphenomenon.

FIG. 4 is an overlay schematic diagram showing the transparent thincolor plate of CMY tricolor.

When the white light W (containing the RGB tricolor lights) irradiateson the green, magenta, yellow, transparent thin plates, the greentransparent thin plate C absorbs the R light in the white light W, themagenta transparent thin plate M absorbs the G light in the white lightW, and the yellow transparent thin plate Y absorbs the B light in thewhite light W. In the end, the white light W is totally absorbed andbecomes opaque and present black.

Please refer to FIG. 4A, the mathematics schematic diagram showing theCMY colorants and RGB color lights.

FIG. 4A illustrates that, after the equal mixing the three kinds oforiginal colorants of green, magenta and yellow, the black colorant willbe obtained, i.e., (C)+(M)+(Y)=(BK). That is, the black colorantexplains the phenomenon that after the white light W (composed of RGB)absorbs RGB tricolor lights, it will present black.

After the equal mixing the tricolor colorants, the black color will beobtained, i.e., the formula could be written as (Y)+(M)+(C)=(BK).

Firstly, If mix the yellow and the magenta, the inter-red will beobtained, and then mix the inter-red with cyan, and the above formulamay be changed into: (R)+(C)=(BK)

If after mixing two kinds of colorants, a black is obtained, then thesaid two kinds of colorants are called as complementary colorants, andthe said colors are called as complementary colors.

That means, the black will be obtained by adding the red to the cyan, orby adding the cyan to the red. The red and the cyan are a couple ofcomplementary colors. Besides, in the colorants, the magenta and thegreen, the yellow and the blue are respectively complementary colors.

Please note that, due to various proportion changes of tricolors, thecomplementary colors are more than the above couples.

As long as after the two kinds of colorants are mixed, the black isobtained, and the said two kinds of colorants are complementarycolorants. Any kind of colorant has its counterpart complementarycolorant.

The application of complementary colors is the main principal of themanufacturing method of the present embodiment.

Fox example, in the manufacture process, when a finished product need tobe darkened (to be blacked) somewhere, it is no need to use black(carbon black), but adding a complementary color of its original colorwill do.

The additive color method is a method for presenting the color of themixed color lights. After the color lights mixed, not only the color isdifferent from each color lights took part in, but also the brightnessis increased. The subtractive color method is a method for presentingthe color of the mixed colorants. After the colorants mixed, not onlythe new color is generated, but also the brightness is decreased.

The additive color method is the color effects of more than two kinds ofcolor lights stimulating the optic nerves of human being, while thesubtractive color method is the color effects of the stimulation of somekinds of color lights which are subtracted from the white light or otherpolychromatic lights. There are basically three couples of complementarycolors from the view of complementary relations, i.e., R-C, G-M and B-Y.In the additive color method of the color lights, the white light isobtained through the adding of complementary colors. In the subtractivecolor method of the colorants, the black light is obtained through theadding of complementary colors.

The tricolors of the color lights are red (R), green (G) and blue (B).The tricolors of the colorants are cyan (C), magenta (M) and yellow (Y).It is the color light that the people always see. It is certain that thetricolor of the colorants must be associated with the tricolor of thelights.

The cyan, the magenta and the yellow can easily change the absorbedcapacity toward the red, the green and the blue by changing their ownthickness (or density), and further successfully control the quantity ofthe tricolor lights entered into the human eyes.

To control reflection lights by using the cyan, the magenta and theyellow is actually to utilize them to selectively absorb some spectrumcolors from light source spectrum, to accomplish adding mixture coloreffects with the left color lights. In the meantime, it is the selectionand identification of the red, green and blue of the color lighttricolor. The red, the green and the blue of the color light tricolorsare uniform with the cyan, the magenta and the yellow of the coloranttricolors, and they have common natures, and they are the two sides ofan object. It is certain that they all get bigger color range. In aword, it is the color lights that entered into the human eyes.

Please refer to FIG. 5, the typical color characteristic curve showingthree receptors of human being.

As shown in FIG. 5, the reception of color-receiving cells of humanbeing toward the red, the green and the blue are respectively the redlight area, the green light area and the blue light area.

When the eyes receive different quantity of colors, the feelings towardthe colors are determined by the bigger color light among the threekinds of color lights. The receiving-sensitive are showed in thecoordinate axis, wherein, the Y-axis representing the sensitiveness ofthe optic nerves of human being, the X-axis representing the visiblewavelength table.

As shown in FIG. 5, the wavelength of 400 nm could make the eyes receivethe blue B and the red R receptors at the same time. As a result, anaverage color feeling is felt in the eyes, and that is the purple. Withthe wavelength increasing, the reception quantity of the blue receptorincreases gradually, so the feeling toward purple is replaced by theblue. When the wavelength reaches 480 nm, as the equal quantity of redand green are received together with part of the blue, then the white isgenerated. Meanwhile as another part of blue left, so the pure blue B1is received in the end. Due to the disappearing white light generated bythe unequal quantity of the red light, the green light and the bluelight, the feeling toward the blue is the decreasing purity (saturation)blue. When the wavelength continues to reach 600 nm, the receptiontowards the red light and the green light is strong, while the bluelight is attenuated, so the reception towards the yellow and the greenis received. Reaching to 600 nm, the reception towards the blue light ishardly received, only the equal red R and green G, and the receptiontowards yellow Y are received. When the wavelength continues to reach700 nm from 600 nm, the reception towards the red light and the greenlight is attenuated gradually, while the reception towards green isevident, and the yellow light with the red light is received by theeyes. When the wavelength reaches 700 nm, only the red light isbasically received.

So, the general colorants are not the single tinge.

The long wave after the red light in the visible light is the infraredarea, and in the present embodiment, it refers to the area from 780 nmto 1000 nm, which is the effective wavelength received by the ImageSensor of the CCD camera, and the light there is normally called as theinfrared ray.

Well known in the industry chromatics, if mix a colorant with anothercolorant and the mixture presents black, these two colorants are calledas the complementary colors.

But in the transparent complementary colorants, the mixture colordiffers greatly. For example, the transparent yellow+the transparentblue=the emerald green, the transparent red+the transparent yellow=thebright orange, the transparent blue+the transparent red=the brightpurple. Evidently, no black presented.

From the energy perspective above, the light energy decreases after thecolorants are mixed, then the mixture color is certain darker than theoriginal color. If the density (dosage) of the transparent colorant isnot enough or too tenuous, the light energy decreases little after thecolorants mixed. Increasing the density to let the light energy decreaseto a certain extent, the similar black will be obtained.

As mentioned above, that is the reason why the transparent tricolor CMYis used.

Simply, the “transparent” of the transparent tricolor CMY colorants ismainly to let the infrared ray transmit through. The mixture of thetransparent tricolor CMY colorants is mainly to absorb the visiblelights and present black.

The following explains the transparent resin 12.

The transparent resin 12 must be highly transparent, so the surfacethereof must have perfect quality that there are no stripes, no pores,no drifting white, no fog areola, no black spots, no color change, nopoor gloss and so on.

There is commonly minute surface in the transparent polymer and thatmakes light scattering happen, and the typical example is the crystalstructure. For example, water and ice are both made up of H₂O.Generally, water is transparent, but ice is opaque. The reason is thatice has a crystal structure and it makes the light scattering happen,which let the light transmit through decreasingly, and water isotherwise. So, non-crystal structure is one of the factors to betransparent.

In industrial plastic, the well transparent resins are PMMA (transparentdegree 93%), PC (transparent degree 88%), PS (transparent degree 89%),CR-39 (transparent degree 90%), SAN resin (transparent degree 90%), MSresin (transparent degree 90%), TPX (transparent degree>90%). Besides,MAS, PET, PP and PVC and so on, they all have good transparent degree.As long as a compatible transparent plastic or generally transparentcolorants are found, the need of capable of transmitting infrared ray isreached in the present embodiment.

In the above said generally transparent resin 12, the transmittance ofthe light not only includes the visible lights with the wavelength from380 nm to 780 nm, but also actually covers up the near infrared areawith the wavelength from 780 nm -1200 nm.

The transparent quality of the visible lights and the infrared ray inthe polymer is generally influenced by the reflection, absorption, andscattering of the lights.

When the lights reach the polymer, a part of the lights is expensed onthe surface due to the reflection. When the light vertically incidentfrom the air with a refractive index n1 (n1=1) into a polymer with arefractive index n2, the surface reflectivity R could be presented asR=(n−1)²/(n+1)². The data shows that, the refractive index of thetransparent acryl PMMA (organic glass) is 1.49, and the calculationsurface reflection R is about 4%. The entire light transmittance of PMMAis about 93%, and the loss of the light is mainly due to the surfacereflection, but the absorption and scattering inside is very minor.

When the light reaches the polymer molecule, the molecule will absorbits energy and generate whirligig, which generate light absorption anddecrease light transmittance. The scattering at the same time will alsodecrease light transmittance heavily.

The intrinsic scattering of the polymer is in direct proportion to the8^(th) power of the refractive index, and is inversely proportional tothe 4^(th) power of the wavelength. Therefore, the loss of materialscattering is less in the less refractive index, and the effect onscattering in the visible area with long wavelength is less. The effecton scattering in the infrared area with long wavelength is less almostto zero. This is very important for the embodiment of the presentinvention.

Furthermore, the impurity which are generated or administrated in theprocess of the manufactures will decrease the light transmittancebecause of the scattering. The data of the manufacture factory showsthat, the impurity in the optical level PMMA is only one of the tenth ofthe general molding level PMMA, and this is why the present embodimentsuggests using the optical level PMMA. In the practical application, thelight transmittance is largely influenced by the fluctuation of theenvironment temperature and the humidity. Generally speaking, the biggerrefractive index of the high molecular polymer is, the bigger thereflectivity is. The uneven configuration of the high molecular polymermakes the microcosmic refractive index uneven optically, and aphenomenon of scattering happens. The refractive index of optical levelis very even.

At present, the transparency of the acryl PMMA (methyl methacrylate) issecond to none in the transparent plastics, and an object can be seenthrough, even when the molding board is 2 m. It has the quality that itcan be pigmented by the dyes freely, very good surface gloss, and noharm to human being.

Spectroscopic light transmittance of the PMMA made by the Rayon of theJapanese Mitsubishi Corporation is increasing near the ultraviolet lightat 250 nm and totally not absorbed in the visible light area. The PMMAresin on the market always has agents against ultraviolet light. Therange of spectroscopic light transmittance in infrared ray is from 800nm to 1600 nm.

First, choose PMMA to do the experiment. PMMA is a kind of amorphousplastic, the high polymer of which arranges in disorder and has nowell-regulated arrangement configuration formed, in the process ofsolidification of which there is no development of crystal nucleus andgrain. The PMMA only has the phenomenon of the high polymer chain beingfrozen. So they are mostly transparent. All amorphous plastic polymershave good light transmittance and lower density. In the crystallinepolymers, as the reflections of the spherocrystal and the vagiformregions are different, the crystalline polymers has bad lighttransmittance and high material density, that means the crystallinepolymers are not suitable to the present invention.

The PMMA acryl boards have good process performance and could be usedeither in the heat molding (including mold press, blow mold, vacuumabsorbing mold) or in the machine process including the drill, lathing,the incision and so on are adopted. The machine scratch and engravingcontrolled by the microcomputer not only largely increase processprecision, but also work out the design and the modeling, which can notbe accomplished by the traditional way. Furthermore, adhesion, painting,metal deposition, dyeing and so on, can also be done, and it is veryadaptable to the present invention.

The following explains the black plastic article 15.

The present embodiment actually refers to the technique of plasticmatching colors. The added colored colorant must not affect the lighttransmittance of the PMMA resin itself. So the “transparent” colorantsmust be used, and the reflection of every colorant does not differ muchfrom that of the resin, so as not to decrease the light transmittance ofthe resin.

The water absorption capacity ratio of the general PMMA at roomtemperature under 100% relative humidity is about 2%, but thepermissible dosage of the injection molding material is beyond 0.1%, sothe factories always prepare dryness before the molding, in order to getrid of water.

In the usual injection molding process, the black mixture material 13 issupplied to the heating jar through a funnel, wherein, which is heatedand dissolved, and then pressed into the metal mold 14 through theorifice by the ejection pressure, wherein, to fill the mother moldthrough the gate and the runner. And it can be taken out after cooling.

The current art on the PMMA coloring process is very mature. Thecoloring work of the present embodiment is done by the professionalfactories, so the manufacture process will not be illustrated.

In the present embodiment, hand over the colorant lists of thetransparent tricolor colorants of cyan, magenta, and yellow to theprofessional factories to choose. The professional factories select thetransparent colored colorants of some special brands and mix saidcolorants with the proportion of one of the third each, and then add asmall amount of the dispersant. Stir the obtained mixture in the mixerto get the powder black colorant 11.

And then the transparent granules 12 of optical level PMMA and thepowder black colorant 11 are stirred in the mixer to get the granules 13of the black mixture materials. Wherein, the proportion between thetransparent granules 12 of PMMA and the powder black colorant 11 is 100to 0.4. (if use other less transparent resins, the proportion may beabout 100 to 0.2).

In the present embodiment, hand over a prepared metal mold 14 to aplastic factory to manufacture a finished product which will be used inthe experiment later. The internal mold of the metal mold must bepolished precisely, in order to make the black plastic 15 have a verysmooth surface plane that the scattering of the incident infrared raydue to the non-smooth surface could be avoided.

The alternative resin in the application of the present embodiment is PC(Polycarbonate), and its transparency is a little worse than that of thePMMA (about 92%).

The differences between them as follow:

The shortcomings of PMMA: higher water absorption, less heat resistance,can't bear the impact well, easy to light-off.

The shortcomings of PC: poor formability.

Because of higher viscosity of PC, its forming temperature is alsohigher. But it does not require particularly difficult formingtechniques. The benzene ring in the molecular structure of PC isasymmetrical in the three-dimension, so the amorphous have goodtransparency, and the light transmittance in the visible light area isup to 90%. In addition, PC is also difficult to be ignited (also knownas the fire rating).

In the high-performance transparent resin invented for the CD-ROM, itsmolecular structure is characterized as the ester ring. It has the samecharacteristics of birefringence with that of PMMA, but its waterabsorption is much lower than that of PC, about 1%. Other representativetransparent resins are APO developed by the Japanese Mitsui Chemicalswith a light transmittance up to 90%, ZEON developed by the JapaneseZEONEX with a light transmittance up to 91%, ARTON developed by theJapanese Synthetic Rubber Company with a light transmittance up to 92%.

As the PC materials have hygroscopicity, the drying before theprocessing is very important.

In the injection molding, as the mixture of PC and the black colorant 11has a higher viscosity than that of the PMMA, the forming temperatureshould be higher. However, it does not particularly require difficultmolding technology. It can be formed in accordance with thespecifications provided by the manufacturer, or be produced by OEMmanufacturers.

So, again, the inventor hand over a prepared metal mold 14 withprecisely polished internal mold to a plastic factory to manufacture afinished product to be used in the experiment.

To learn more about the black plastic article 15, as well as itsapplication, the present embodiment designs a color camera, which couldtake the clear color image and the clear infrared image respectively inthe visible light area and in the infrared ray area. Especially, suchcamera could be used in the infrared transmittance photography to avoidthe overlay of the visible image and the infrared image.

Please refer to FIG. 6, the schematic diagram 61 showing a common CCDcolor camera filter.

FIG. 6A is a schematic diagram 62 showing a previous patent CCD colorcamera filter. FIG. 6B is a schematic diagram 63 showing the presentembodiment CCD color camera filter.

FIG. 6 is a schematic diagram 61 showing a common CCD color camerafilter, including the image sensor 611 (including quartz glass), thephotographic lens 612 and the infrared ray cut filter 613. When thevisible light enters into the image sensor 611 from the lens 612, onlythe visible light is accessible, and the infrared ray will be cut off.When the infrared ray in the visible light is mainly filtered, the truecolor images can be obtained (not the reddish color).

Wherein, FIG. 6A is a schematic diagram 62 showing a CCD color camerafilter of a previous patent, which includes the image sensor 611, thephotographic lens 612, the infrared ray cut filter 613 and the colorlesstransparent glass 614.

When the visible light enters into the image sensor 611 from the lens612, if the infrared ray cut filter has been installed on, only thevisible light is accessible, and the infrared ray will be cut-off. Thenthe true color images can be obtained.

The visible light could transmit through whatever there is transparentquartz glass or not. The installed transparent quartz glass is used toreplace the vacant position to avoid the difference in the optical path.

When the infrared ray cut filter 613 is removed, the camera of FIG. 6Ahas almost the same functions as those of the general black-and-whitecamera, which means it could sense the visible light and the infraredray at the same time.

FIG. 6B is a diagram 63 of the cut filter of the CCD color cameramentioned in the embodiment of this invention, wherein the cameraincludes an image sensor 611, a photographic lens 612, an infrared raycut filter 613 and an infrared ray pass filter 615. When the visiblelight transmits into the image sensor 611 through the photographic lens612, if the infrared ray pass filter is installed, then only theinfrared ray could pass, while the visible light and other infrared raywill be cut off. And then if the infrared ray cut filter is installed,then only the visible light could pass, while the infrared ray will becut off.

Hence, the differences are listed as follows with the reference of FIG.6 to FIG. 6B:

The device of FIG. 6 has a fixed infrared ray cut filter 613, while thedevice of FIG. 6A has a removable infrared ray cut filter 613.

The device of FIG. 6B has a removable infrared ray cut filter 613 and aremovable infrared ray pass filter 615.

Embodiment 1

Please refer to FIG. 7 which shows a plate 710 of a black plasticarticle.

The plate 71 is made of a black colorant 11 obtained by mixing theoptical level transparent colorant of CMY together with an equalproportion. Mix said black colorant 11 into the optical leveltransparent resin PMMA 12, and then mold the obtained mixture with ametal mold to get the black plate 71 used in the experiment.

As shown in FIG. 7, the black plate 71 has a smooth surface which hasthree step-thick blocks, wherein the thickness of the blocks 711, 712and 713 are respectively 1 mm, 2 mm and 3 mm.

Now, handing the prepared black plate 71 closely to the eyes and thenobserving the lamp across the black plate 71, it could be found that thelamp is presented blue, purple-like, brown-like respectively observedthrough the blocks 711, 712 and 713. If the amount of the black colorant11 is increased, said colors will be changed approaching to the black.Hereby, the color of the black plate 71 is named as the similar color ofthe black.

The black plate 71 manufactured by this method is mainly used to absorbthe visible light. It does not focus on the how dense the concentrationsof the black is, which degree the absorption is, while it focuses on theblack plate is opaque to the human eyes in order to achieve the opaqueeffect.

If put a deep blue transparent plate onto a bottom the main color ofwhich is black, the deep blue transparent plate is seen as black byhuman eyes. That indicates that the visible light transmits through thedeep blue transparent plate and the black color seen by human eyes isreflected from the black bottom.

In order to explain the difference between the transmittance of thevisible light and that of the infrared ray, mix the black colormasterbatch (carbon black) used in the common plastic instead of theblack colorant 11, together with the optical level transparent resinPMMA, and then mold the obtained mixture with the metal mold used beforeto get a pure black plate 72 with the same bulk.

It is necessary to prove that the black plate 71 manufactured by themethod of this invention has different phenomenon of light transmittancefrom the pure black plate 72 with the common inorganic black colorant.

Please refer to FIG. 8, the schematic diagram showing the colorphotography of the black plate 71.

The device of FIG. 8 includes a video display 81, a color camera 82 anda black plate 71.

When the infrared ray cut filter 613 is installed onto the color camera82, only the visible light could transmit through, while the infraredray is cut off and could not pass through.

The visible light transmit through the black plate 71 and then into thecolor camera 82, wherein the visible light includes the lights 7111,7121 and 7131 which are through the blocks 711, 712 and 713respectively. And the lights are transported to the video display 81after entering to the color camera 82, and then all generate the visiblelight image 7181 of the plate 71.

When the infrared ray pass filter 615 is installed onto the color camera82, only the infrared ray could transmit through, while the visible iscut off and could not pass through.

Please refer to FIG. 8A, the schematic diagram showing the infraredphotograph of the black plate 71.

Sandpaper the surface of the middle block 712 of the black plate 71 toprocess the smooth surface into the rough surface. Meanwhile, keep thesurfaces of the other two blocks 711 and 713 smooth.

The infrared ray transmit through the black plate 71 and then into thecolor camera 82 to be transported to the video display 81 thereafter,wherein the infrared ray includes the rays 7111, 7121 and 7131 which arethrough the blocks 711, 712 and 713 respectively. The generated image ofthe middle block 712 is an opaque white infrared image, while those ofthe side blocks 711 and 713 are both transparent infrared images.

The middle block 712 of the black plate 71 presents an opaque whiteinfrared image mainly due to the reason that the rough and not smoothsurface thereof will cause the incident infrared ray scattered on thesurface. Here, the scattering is also called as diffuse reflection. Andas the infrared ray has already been scattered, it could not transmitthrough or will not have enough throughput to generate an infraredimage.

That means it is necessary to polish the internal mold of the metal mold14 used to mold the black plate 71, so as to obtain a black plate 71with smooth surface. That is the key to let the infrared ray transmitthrough.

Besides, as there are two different media (air and plate 71), therefractions in the two media make the transparent image of the plate 71presents a plate 71 with clearly outline around after being transmittedinto the color camera and transported to the video display 81. Theinfrared image 7182 of the transparent plate 71 could be seen in saidoutline

That means, if pattern the plate 71 purposely to form rough words ordesign on the surface thereof, after the image of the plate 71 has beentransported by the color camera 82 to the video display 81, such imagepresents the opaque and clear words and design.

Please refer to FIG. 9, the schematic diagram showing the infraredphotograph of two different black plates.

The device of FIG. 9 includes a black plate 71, a pure black plate 72, acolor camera 82 and a video display 81.

When the infrared ray pass filter 615 is installed onto the color camera82, only the infrared ray could transmit through, while the visiblelight is cut off and could not pass through.

In the incident infrared ray transmitted through the black plate 71,most part of the infrared ray 7192 on the same side of the color camera82 has disappeared when transmitting through the black plate 71, i.e.,has not entered into the lens of the color camera 82. On the oppositeside of the color camera 82, i.e., the back region of the black plate71, the infrared ray 71921 transmits through the black plate 71 andenters into the color camera 82 to generate an infrared image 71922 ofsaid black plate 71 on the video display 81.

In the incident infrared ray transmitted through the pure black plate72, most part of the infrared ray 7292 on the same side of the colorcamera 82 has reflected on the surface of the pure black plate 72 andentered into the color camera 82, then generated a transparent infraredimage 72922 of said pure black plate 72 on the video display 81. On theopposite side of the color camera 82, another part of the infrared ray72921 has disappeared after being reflected on the surface of the pureblack plate 72, i.e., has not entered into the lens of the color camera82.

Hence, on the video display 81, there are the transparent infrared image71922 of the black plate 71 (just like a transparent glass) and theopaque white infrared image 72922 of the pure black plate 72 (just likean opaque black glass).

The light is selective absorbed by the objects, which is the main reasonfor the color of objects. In some opinions, the red opaque plate 16 isred because of the irradiation of the white light, and the red opaqueplate 16 has no color itself. It is the light that is the source of thecolor. If the red surface is irradiated with the green light, it willpresent black, because the radiation in the wavelength of the greenlight is totally absorbed. If the red surface is irradiated with theinfrared ray, it will present colorless (non-color), because the redsurface only reflects the red light, and as the infrared ray has no redlight to be reflected, the red surface will has no color. Hence, theobject will present different color under the irradiations of thedifferent components of the spectrum of visible light. But if the objectis irradiated by the infrared ray, which is composed of the redspectrum, the object will present colorless. 19

If the infrared energy of the color camera is too little to generate aclear infrared image, an assisted infrared light source could be used toirradiate the objects (the plate 71 and 72) directly or indirectly toincrease the environmental infrared energy.

When mentioning the cut filter in the color camera 82, what is thedifference between the cut filter 62 of the previous patent in FIG. 6Aand the cut filter 63 of this invention in FIG. 6B?

In order to explain the difference between FIG. 6A and FIG. 6B and tosatisfy the practical application, it is necessary to use a large blackplate.

The casting method and the extrusion method are normally used inmanufacturing the large PMMA black plate. The US company Swedlowresearched in the method of continuously producing the transparent PMMAplate with the metal mold made of stainless steel. Such method hasalready been granted for patent (U.S. Pat. No. 3,376,371), but it isunsuitable for producing the thick plate.

In the casting method, two large inorganic glasses are used as mold witha close pad, such as the soft vinyl chloride, inset along the peripheryof two large inorganic glasses. The material of the close pad should beinsoluble in the polymer paste made of PMMA and the transparent coloredcolor masterbatch, should be harmless to the polymer material. Even ifthe polymerization is completed, the close pad should not break away.And along the polymerization of the paste, the volume contracts and theclose pad has the ability to be squashed. Hence, the hardness and theshape of the close pad must be suitable, or the produced large PMMAblack plate will have irregular concave, or the paste will leak out inthe polymerization.

Heat the mold with the paste inside either in the air bath or the waterbath for about five hours under 70° C. to make the polymer besolidified. The first finished product has air bubbles inside. As thepolymerization heat could not be removed in time, the polymer paste isin the state of boiling that the bubbles are generated. This situationwill be improved if the polymerization time is extended and thepolymerization temperature is reduced. The two ends of the two largeinorganic glasses are clamped by a clip.

As mentioned before, the inventor of this invention entrusted a colorantmanufacture company to produce the black colorant by mixing the opticallevel transparent liquid colorants with the CMY tricolor together, andthen entrusted a PMMA plastic manufacture factory to product a largeblack plate by casting. Such large black plate is used in theapplication experiment.

Please refer to FIG. 10, the penetration schematic diagram of the cutfilter of the CCD color camera of a previous patent.

The device of FIG. 10 contains a color camera 82, a video display 81, alarge black PMMA plate 105, an object 101 and an object 102, wherein,the color camera 82 has a transparent glass 614. The object 101 and theobject 102 are placed on both sides of the large black plate 105.

Here, as the color camera has a transparent glass 614 on, both thevisible light and the infrared ray could transmit into the lens of thecolor camera 82.

As the visible light image 1011 of the object 101 could not transmitthrough the black plate 105, the surface of the black plate 105 reflectssaid image into the color camera 82 to present a visible light image ofthe object 101 on the video display 81.

As the infrared image 1012 of the object 101 could transmitted throughthe black plate 105, said image could not enter into the color camera82. As a result, no infrared image of the object 101 is presented on thevideo display 81.

As the visible light image 1021 of the object 102 could not transmitthrough the black plate 105, the surface of the black plate 105 reflectssaid image back. Hence, said image could not enter into the color camera82. As a result, no visible image is presented on the video display 81.

As the infrared image 1022 of the object 102 could transmit through theblack plate 105 and then enter into the color camera 82, the infraredimage of the object 102 is presented on the video display 81.

As a result, the visible image of the object 101 could be seen on thevideo display 81, meanwhile the infrared image of the object 101 couldalso be seen. That means the two images overlap.

Of course, if the environmental visible light of the object 101 is verystrong (for example, there is an assisted white light source), thevisible image of the object 101 will cover the infrared image of theobject 102, and only the visible image (colored image) of the object 101could be seen on the video display 81.

On the contrary, if the environmental infrared ray of the object 102 isvery strong (for example, there is an assisted infrared ray source), theinfrared image of the object 102 will cover the visible image of theobject 101, and only the infrared image (black-and-white image) of theobject 102 could be seen on the video display 81.

If the object 101 and the object 102 are placed in the same environment,for example in the sunlight from the outside which almost has enoughvisible light and infrared ray to be provided for generating the imagesin the color camera 82. Here, it could be seen on the video display 81that the two images of the object 101 and the object 102 are overlapped.

In order to reduce the overlap of the two images, this invention herebymakes an improvement that replaces the transparent glass 614 with aninfrared ray pass filter 615.

Please refer to FIG. 11, the penetration schematic diagram of the cutfilter of the CCD color camera of the present invention.

As shown in FIG. 11, the infrared ray pass filter 615 could only let theinfrared ray transmit through, but not the visible light.

That means, the visible light image 1011 of the object 101 reflects onthe surface of the black plate 105, and then will be stopped by theinfrared ray pass filter 615 before it reaches the color camera 82.Hence, no visible light image could be generated then. At the same time,the infrared image 1012 of the object 101 transmits through the blackplate 105. So the infrared image 1012 of the object 101 could not reachthe color camera 82 for the image generation.

As a result, the image of the object 101 can no be seen on the videodisplay 81.

As the visible image 1021 of the object 102 is reflected on the surfaceof the black plate 105, it could not enter into the color camera 82 forthe generation of the image. While the infrared image 1022 of the object102 transmits through the black plate 105, so it could reach the colorcamera 82 for the image generation.

As a result, the image of the object 102 can be seen on the videodisplay 81.

In this way, the comprehensive result is that, the overlap images of theobject 101 and the object 102 can not be seen. Furthermore, thetransmittance function emphasized in this invention is carried out.

The overlap images of the object 101 and the object 102 can be seen onthe video display 81, one is the visible light image of the object 101,and the other is the infrared ray image of the object 102. When theinfrared ray pass filter 615 is added, the visible light image of theobject 101 is cut, so the overlapping images are reduced.

However, if the object 101 is in the infrared ray environment, (or theinfrared ray is greater than the visible light), do the two overlappingimages of the object 101 and the object 102 can be seen?

The answer is uncertain!

Please refer to FIG. 12, the schematic diagram showing the imagegeneration situation of the infrared ray pass filter.

First of all, if the object 101 is in the infrared ray environment (withthe middle wavelength of 850 nm), and the wavelength of the cut infraredray filter 6151 is 940 nm, that is to say, the infrared ray with thewavelength before 940 nm will be cut off, and only the infrared ray withwavelength after 940 nm will transmits through.

So, the infrared ray image 1013 at 850 nm of the object 101 can notreach the color camera 82 for the generation of the infrared ray imageof the object 101 on the video display 81.

In fact, a little of the infrared ray image 1013 at 850 nm of the object10 will be reflected on the black plate 105, and most part of theinfrared ray image 1012 will transmit through the black plate 105.

Also, if the object 101 is in the infrared ray environment (with themiddle wavelength 850 nm), and the cut infrared ray filter 6151 is also850 nm, and then, the two overlapping images of the infrared image 1013of the object 101 and the infrared image 1022 of the object 102 can beseen again. The method to reduce the two overlapping images is to changethe infrared pass filter 615 into the infrared cut filter 6151, which isto make the wavelength of the infrared ray pass filter bigger than thewavelength of the infrared ray (850 nm) environment wherein the object101 is.

In this embodiment, the obvious effect will occur when an assistedinfrared ray source with the same wavelength of the cut filter 6151 isadded into the environment of the object 102. And the infrared rayimages 1022 at 940 nm are enhanced and powerful enough to successfullyreach the color camera 82 and present a very clear image.

Here, this infrared ray pass filter 6151 which could cut the infraredray of certain wavelength, is called as the infrared ray pass filter 615with cut function.

When the light meets the color particle, the direction of the light willbe changed, and this phenomenon is called the scattering. The changedangles are correlative with the size of the color particle and therelative refractive index between the color particle and the medium.

The following will explain the concept of “transparent” and “opaque”with the scattering phenomenon. The black plastic article 15 of thepresent embodiment is opaque for the visible lights and is transparentfor the infrared ray.

First of all, the “transparent” and “opaque” of the visible light willbe explained.

Please refer to FIG. 13, the cross-section diagram of a black colorant(carbon black).

FIG. 13 is a cross-section of the carbon black, wherein, when thevisible lights enter into the internal carbon black particles of carbonblack (black spots in the drawing), most of which are absorbed, andfewer are scattered by the diffraction around the carbon blacks. Due tothe excessive consumption of the light energy, the visible lights cannot enter into the deep and transmit through, and present opaque atlast.

Please refer to FIG. 13A, the cross-section diagram of a plastic article15.

The FIG. 13A illustrates that, the visible lights enter into theinternal particles of the black plastic articles, (black spots in thedrawing), most part is absorbed, and fewer are diffracted around theparticle. This is because the colorants and the resins of the blackplastic articles are transparent. The drawing shows that, the blackspots are scare and the distribution is loose, wherein, a minute ofvisible lights transmit through and present a little transparent. Forexample, the black plate 105 looks a little blue.

Please refer to FIG. 13B, the cross-section diagram of a black colorant(carbon black).

FIG. 13B is a thin (with a relatively fewer black articles)cross-section of the carbon black, wherein, when the visible lightsenter into the internal carbon black particles of carbon black, mostpart is absorbed, and fewer is diffracted around the carbon blackparticles (diffraction is one kind of scattering) and then transmits outthrough the membrane interface. A minute of visible lights transmitthrough and present a little transparent.

Please refer to FIG. 13, the cross-section diagram of a plastic article15.

The device of FIG. 13C is a black plastic article 15, wherein, when thevisible lights enter into the internal particles of the black plasticarticle 15, one part is absorbed, and the other part is diffractedaround the particles. Most of the visible lights transmit through andpresent a little more transparent.

As shown in FIG. 13, the incident lights of the three carbon blacks arescattered in clouds of the carbon black particles and do not have enoughenergy to transmit into the deep, so it present opaque. But as shown inFIG. 13A to FIG. 13C, the incident lights of three carbon blacks arescattered in loose carbon black particles and have slightly enoughenergy to transmit into the deep, and a minute of visible lightstransmit through and present a little transparent.

Secondly, the “transparent” and “opaque” of the infrared ray will beexplained.

The scatterings of fine particles follow the Rayleigh scattering Law:the intensity of the scattering lights is negatively related to the foursquare of the wavelength. The wavelength of the blue light is comparablyshort and is easily to be scattered, while the red light is not thecase. The occurring scattering when the size of the common colorant fineparticles is smaller than one of the tenth of the wavelength of thevisible light is called the Rayleigh scattering. So the fine particlesalways show Rayleigh scattering.

According to the Rayleigh scattering Law, compared with the visiblelight, the scattering of the infrared ray is very small, because thewavelength of the infrared ray is longer than that of the color light.

So, if there is a minute of visible light transmitting through thedevice of FIG. 13A to FIG. 13C, it must present transparent in theinfrared ray.

As shown in FIG. 13, as the wavelength of the infrared ray is longerthan that of the visible light, the infrared ray has not enough energyto enter into the deep and then to transmit through. So the infrared raypresents opaque in the colorant carbon black.

If the device of FIG. 13A is a black plastic article, then most of theincident visible lights are absorbed, and the black plastic presentopaque in the visible lights. However, a small amount of visible lighttransmits through, and it is not easy to be seen without the stronglight (or a special light source) background. This case is mentionedabove, and can be accepted for the present embodiment. So it is alsocalled to present opaque in the visible lights.

Therefore, the black plastic article 15 presents opaque in the visiblelights, but transparent in the infrared ray. The color camera 82 asshown from FIG. 8 to FIG. 12, when it carries out photography on thevisible lights or the infrared ray, the impact point of the focus willbe different, so there is a need to readjust the focal length.

To prove the utility of this invention, please refer to the FIG. 14which is the diagram of the animals and plants observation darkroom.

In FIG. 14, there are a color camera 82, a video display 81, anobservation darkroom 141 made of the black plastic article 15 used inthe animals and plants experiments, a table 142 with the observationdarkroom 141 thereon, an assisted infrared light source 143. On theobservation darkroom 141, there is a door 1411, a ventilation device1412 and an exhaust device 1413. The desktop of the table 142 is atransparent glass plate.

When it is necessary to observe the experimental changes of an animal ora plant in the dark and no light condition, the observation darkroom ofthis invention could be adopted together with the color camera 82 withan infrared ray pass filter 615 inside, an assisted infrared lightsource 143 and a video display 81 to achieve a better effect.

For example:

1. During the observation period, the door 1411 could not be opened tosatisfy the need of observation by eyes, because the light transmittedinto from the open door will affect the experiment.

2. If is necessary to observe and record the development and the changeof a special period, or a long time of observation and recording, or acondition of continuous moment change.

For example, a little white mouse that has taken special drugs is putinto the observation darkroom 141 through the door 1411, and the growthand action of the mouse are observed in the dark. The air convection isprovided by the ventilation device 1412 and an exhaust device 1413. Aspeople can not open the door 1411 for the observations with eyes, theuse of the color camera 82 been installed an infrared ray filter 615 on,is freely moveable from the exterior of the observation darkroom, inorder to find a suitable observation point of view for the transmittancephotography monitoring and observation.

When the animals (white mice) in the observation darkroom run around,the color camera 82 and the assisted infrared ray source 143 through thevideo display 81 can be freely moved by the experiment staff, until theright position can be found to carry out the observation and photographbeing taken.

If necessary, observe the abdomen after the animals lie down from apiece of transparent glass of the desk 142, and the photographs can betaken.

The growth process of a special plant in the darkroom can be observedfrom the observation darkroom, or the photosynthesis and the record ofgrowth phenomenon in the particularly built-in light source can beobserved.

In addition, in the public safety equipments, such as suspicious objectsplaced in the trash and temporary leave-box in terror areas, theinfrared photography can also be used to carry out long-range detection.

The observation darkroom 141 used in animals and plant tests presentsopaque in the visible lights, but presents transparent in the infraredray.

That explains one of the application values of black plastic articles.

Please refer to FIG. 15, the schematic diagram of the application in thehiding identification.

In FIG. 15, a transparent colorless plastic plate 152 is inserted intothe middle area between two black plastic plates 151. Write the words“ABC” with a black color pen on the surface of the transparent colorlessplastic 152. As shown in FIG. 15A, the transparent colorless plastic1521 has the pattern of text on.

Under this situation, when the infrared ray pass filter 615 is installedon into the inside of the color camera 82:

it could be seen on the video display 81 that there are three words“ABC” hided inside of the black plastic plates 151.

This sandwich structure could be used together with the transmittancephotography of the color camera 82 in the anti-counterfeitingsurveillance field.

Of course, there are other applications of this sandwich structure. Forexample, attach or cave some patterns of text on the surfaces of some ofa plurality of black plastic plates 151, then use the color camera 82photographs these black plastic plates 151. The image of the photographon the video display 81 is an infrared image with more hierarchicalstructure.

In the previous technology, the black colorant (carbon black) could notlet the infrared ray transmit through due to the scattering of the blackcolorant (the particles of the carbon black are too large) and thescattering of the opaque resin (the energy of the infrared ray is notenough).

That means if we want to improve the black colorant (carbon black) ofthe previous technology which could not let the infrared ray transmitthrough, the main method is using the grinded black colorant sold on themarket (the particles of this black colorant is smaller enough to reducescattering thereon) and the transparent resin to achieve the idealsituation.

Hence, the inventor bought the grinded black colorant (commonly known asthe transparent black, hereinafter, the transparent black) to replacethe three transparent colorants with CMY colors. Then entrust theplastic produce factory to mix this transparent black into thecompatible PMMA to mold another black plate. Use this new black plate todo the experiment shown in FIG. 8 and FIG. 8A again. It is found thatthe new black plate has the same infrared transmission effect as that ofthe black plate 151.

Obviously, the qualities of the transparent black of the differentmanufacturers are different that a number of experiments must be takento obtain a better processing method. The smaller the particles of thetransparent black are, the better absorption of the visible light thereare. But, as shown in FIG. 13 to FIG. 13C, in the same unit, if theparticles are too small, the density of the particles will reducedrelatively, which will let too much visible light pass through. Asknown, the less the visible light pass, the more opaque human eyes feel.

To sum up the results of the experiments above:

A method for manufacturing black plastic article capable of transmittinginfrared ray mainly is mixing the transparent colored colorant and thetransparent colorless resin together to obtain a mixture which will beprocessed by machines thereafter. The obtained products are able toabsorb the visible light and let the infrared ray transmit through. Thismanufacturing method includes three steps:

Step 1: mix the transparent colored colorant together to compose theblack colorant 11;

Step 2: mix the black colorant 11 into the transparent resin with aproportion to compose the black mixture material 13;

Step 3: process the obtained black mixture material 14 by molding withthe mold having a polished internal mold, casting with two plates withsmooth surfaces or by other mechanical methods.

Please refer to FIG. 2B of the step 1. Mix two colorants (for example,the colorants with complementary colors) together and stir the obtainedmixture to compose a transparent colorant with similar black color,wherein the colorants mixed are colored by the transparent colorantswith CMY tricolor.

In the step 1 above, the colored (black) transparent colorant is agrinded black colorant that the diameter of the particles after thegrinding is one of the tenth of the original diameter before thegrinding. Said grinded black colorant is used to reduce the scatteringthereon.

In the step 1 above, the colored (black) transparent colorant isprocessed by the nano-treatment method to reduce the scattering thereon.The processed particles might be too small that its low density will lettoo much visible light pass through, just as shown in FIG. 13A to FIG.13C. This situation is contrary to the purpose of this invention thatthe visible light is stopped.

In order to avoid the products are too transparent to the visible light,other transparent colored colorants could be used together. After a fewtimes of the experiments, it is found that when the general blackcolorant after being grinded has a particle diameter smaller than thewavelength of the visible light, a satisfied infrared image will beobtained in the experiment, just like that of FIG. 8A.

The transparent colored colorant could be a solid, a liquid, a plasm ora paste. As long as such transparent colorants could be mixed to composea mixture with similar black color, the purpose of this invention isachieved.

Therefore, in the step 1, the black colorant is composed of thetransparent colored colorants.

In the step 2, mix the black colorant with the compatible transparentresin with a proportion of 0.4 to 100. Actually, such proportion couldbe adjusted according to the need, if only an acceptable infrared imagecould be generated finally. Such proportion is not limited to the 0.4 to100.

In the step 2, the transparent resin 12 is an industrial resin with thebest transparency, the transparence of which is about 88% or above. Itis very important that in such transparent resin 12, its lighttransmittance not only includes the visible light with a wavelength from380 nm to 780 nm, but also includes the near-infrared field with awavelength from 780 nm to 1200 nm actually.

For example, there are PMMA (transparence 93%), PC (transparence 88%)and other transparent resins. Any resin could be used only if it iscompatible to the transparent colorants.

In the step 3 above, the black mixture material is mainly processed bythe mechanical methods of injection mold, pressing, casting and so on,just like the normal molding process.

In the molding process of the black mixture material 13, a metal moldwith a polished internal mold or other assistant appliances must be usedto manufacture the products with smooth surfaces and various shapes.

The manufactured black plastic article 15 capable of transmittinginfrared ray is mainly used with a color camera 82, the image sensor ofwhich has an infrared ray cut filter 6151 in front. In the transmittancephotography, such color camera 82 is mainly used to reduce the overlapof the image, so as to get a clear object.

Such color camera 82 could be replaced by normal black-and-white camera.

When using the black-and-white camera (sensitive to the infrared ray),if there is interference in the taking the infrared image, an assistedinfrared light source could be used to increase the energy of theinfrared ray over that of the visible light. Hereby, the interference ofthe visible light could be reduced and the overlap of the visible imageand the infrared image could also be avoided.

In practice, based on the application in the observation darkroom shownin FIG. 14, the application in the counterfeiting identification fieldshown in FIG. 15, it could be known that this invention could be used ina wide field and it also could be further used based on the originaluses.

1. A method for manufacturing a black plastic article capable oftransmitting infrared rays and used in infrared transmittancephotography, the article including at least, a black colorant, which iscomposed of transparent colorants or which is a kind of black pigmentwith a particle diameter smaller than the wavelength of visible lightafter being grinded; and a transparent resin used as support; the methodconsisting of the steps of: mixing said black colorant into saidtransparent resin; and forming the black plastic article with a smoothsurface which is capable of transmitting infrared rays.
 2. The method ofclaim 1 wherein the black colorant composed of the transparent colorantsis prepared by mixing and stirring the transparent colorants together,wherein the colorants are compatible with each other and include thecolors of cyan, magenta and yellow.
 3. The method of claim 1 wherein theblack colorant composed of the transparent colorants is prepared bymixing and stirring the transparent colorants together, wherein thecolorants are compatible with each other and include the colors of red,green and blue, or wherein the colorants are compatible with each otherand include at least two of the colors of red, green and blue. 4.(canceled)
 5. The method of claim 1 wherein the black colorant is asolid, a liquid, a plasm or a paste.
 6. The method of claim 1 whereinthe transparent resin is acryl PMMA, polycarbonates resin PC, or othertransparent resin compatible with the black colorant.
 7. The method ofclaim 1 wherein the black colorant is mixed into the transparent resinwith a proportion of 0.4 to 100 to form a mixture which could be useddirectly thereafter, or could be processed into the sticks and then cutinto the grain to form a black masterbatch by the machines or theequipments.
 8. The method of claim 1 wherein the black plastic articlecapable of transmitting infrared rays and having a smooth surface ismanufactured by, being molded with a metal mold, the metal mold having apolished internal mold; or pouring a liquid acrylic into a regionbetween two pieces of inorganic glasses having smooth surfaces in orderto cast a form.
 9. A black plastic article capable of transmittinginfrared rays manufactured using the method of claim 1 in combinationwith at least one camera, the camera adapted to use a removable infraredray cut filter.
 10. The combination of claim 9 wherein the camerafurther comprises an infrared ray pass filter or an infrared ray passfilter with cut function.
 11. (canceled)
 12. The method of claim 1wherein the black plastic article capable of transmitting infrared raysis formed in a plate shape, a film shape or a spatial structurecomprising two or more plates and is used for transmittance photography,anti-counterfeiting, identification of artwork and similar uses.